No large-magnitude tectonic rotations of the Subsilesian Unit of the Outer Western Carpathians: Evidence from primary magnetization recorded in hematite-bearing Weglowka Marls (Senonian to Eocene)

摘要

In the Outer Western Carpathians, previous paleomagnetic studies reported minor and differentiated tectonic rotations of particular thrust-belt segments. Alternatively, large magnitude vertical axis rotations of entire nappes and thrust sheets of regional extent were inferred from the study of Upper Eocene -Oligocene rocks. Paleomagnetic data obtained from the red Weglowka Marls (Senonian to Eocene) indicate that the NE segment of the Outer Western Carpathians was not significantly rotated with respect to the stable European Platform. The Weglowka Marls record a primary magnetization carried by hematite, with intervals affected by secondary reduction processes, associated with reduction to magnetite and pyrhottite. The characteristic remanent magnetization displays dual polarity, passes the fold-test and shows paleomagnetic declinations similar to those expected for stable parts of the European Platform. Anisotropy of magnetic susceptibility (AMS) data show that the analyzed rocks were affected by significant compaction; however they record only a minor tectonic overprint, implying weak internal strain associated with folding and thrusting.